Battery Relocation - Junk In The Trunk

Weekend Tech

I recently picked up a 1970 Z28 Camaro that has been sitting dormant since 1984. I am in the process of improving some of the old mods the previous owner did, and that's what brings us to this point. When I opened the trunk of the car (once I got the key to work that is), I noticed the battery had been moved there. Having the battery in the trunk improves the weight distribution of the car and also helps it hook up by moving some of the weight from the front closer to the rear tires. After seeing the awesome battery hold-down system (a tie strap), I knew this needed to be fixed. I thought it would be a good idea to redo the install and have it conform to NHRA rules. That was until I read the rules.

Excerpts from the 2011 NHRA Rule Book: "Batteries may not be relocated into the driver or passenger compartments. Rear firewall of .024-inch steel or .032-inch aluminum (including package tray) required when battery is relocated in trunk. In lieu of rear firewall, battery may be located in a sealed .024-inch steel, .032-inch aluminum, or NHRA-accepted poly box. The sealed box may not be used to secure battery and must be vented outside of body. Relocated battery must be fastened to frame or frame structure with a minimum of two 3/8-inch-diameter bolts. Mandatory when battery is relocated, an electrical power cutoff switch (one only) must be installed on the rearmost part of each vehicle and be easily accessible from outside the car body. This cutoff switch must be connected to the positive side of the electrical system and must stop all electrical functions including ignition."

So these rules turned a simple freshen-up job into one requiring fabrication of brackets and drilling a hole in the taillight panel for the cutoff switch. Since this car is not destined to live on a quarter-mile track, I ditched the by-the-book mentality and just did a better job than what was there.

To make the job simple when it came to getting the parts, I looked to Summit Racing. Summit not only had everything I needed, they were even nice enough to offer most of it in kit form. The Summit premium battery-relocation kit comes with an NHRA-approved sealed battery box, 20 feet of positive battery cable, 3 feet of negative battery cable, plus all battery terminals and mounting hardware. To the kit I added a Summit battery disconnect switch (250 amps continuous amp rating) and an Optima YellowTop battery. The Optima is an AGM (absorbed glass mat) type battery that is totally sealed and features very low internal resistance for quicker recharge rates. There is a lot more to say about the Optima batteries, so check out the website for more details.

Relocating a battery to the rear of a vehicle.

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Battery Relocation - Junk In The Trunk

1 This is what was lurking under the deck lid on the ’70 Camaro I recently acquired. While having the battery in the back does help in weight transfer, strapping that big chunk of weight in with a tie-down is just not going to cut it. I really want the car to pass tech inspection when I get on a track, and the current setup won’t. Unfortunately, I found it was going to take some fabrication work to make the relocation NHRA-legal, and I just didn’t have the time or energy to do it at this point.

2 As the NHRA rules state, any battery relocated to the trunk must be in a sealed metal or plastic box that attaches to the frame of the car, not just the sheetmetal. Well the framerail of the Camaro is under the trunk floor so this is where the box would need to be, and having it here would make removing the battery a pain in the rear. I decided at this point to scrap the NHRA-legal route and just install the Optima here without the box.

3 For added security and drain prevention, I am installing a master shut-off switch in the trunk. If I was keeping to the NHRA rules, the switch would need to be accessible from outside the car in the event of a problem and it would also need to interrupt the alternator wire as well. Again, since I am just doing this job to clean up previous work, I will not be worrying about those parameters. I disassembled the switch and used the faceplate as a drilling guide. After drilling the large hole with a hole saw and the small one with a regular drill bit, I put the switch in and moved on to getting the battery in place.

4 Without the box there is plenty of room to mount the battery here and still be able to remove it rather easily. I used the metal strap and hardware that came with the Summit kit to dry-fit the battery and determine the location of the holes needed. Basically I used the threaded rod to position the washer, and then I removed the rod and marked the floor right in the center of the washer.

5 Before drilling started, I did look under the car to make sure I wasn’t going to drill into anything like a fuel line or the gas tank. A step drill made the process nice and simple.

6 With that hole drilled I used the strap to figure out the other hole.

7 With the holes drilled I could assemble the battery hold-down stuff. The Summit kit comes with everything you see, along with a large set of washers to spread the load underneath (inset). Again, if this were going to be done to NHRA rules then I would need to fabricate two brackets that come off the framerail and provide mounting points for this hardware.

8 Now that all the components were in place, I could turn to building and routing the cables. The Summit kit comes with 20 feet of positive battery cable, 3 feet of negative battery cable, plus battery terminals. The negative cable was just right, so there was no need to cut it. I stripped the protective sleeve back and then slipped on the terminal. Then, with a borrowed Brute terminal crimper (30 bucks online if you want to buy one) I affixed the terminal to the cable by smacking the top with a hammer, which drives the pin down and crimps the terminal.

9 After applying the provided shrink tube, I routed the cable through the hole the other owner drilled and bolted the cable directly to the framerail.

10 Now for the positive cable. Since I am interrupting the cable with the cutoff switch, I need to make a short section that will go from the battery to one side of the switch. There are a few ways to cut these cables from bolt-cutters to cutoff wheels. The quickest way for me to cut the cable was to use a chisel and heavy hammer. This doesn’t leave the cleanest cut, but as long as I could get the terminal on I didn’t really care. I also realized at this point that I only had two terminals and shrink-tube sections in the kit so I had to take a trip to the store to get two more terminals (they were out of shrink tube). The Summit kit does not account for the cutoff switch, so if you are installing a switch make sure to order two more and some extra shrink tube.

11 With that piece cut, I could then begin the routing process up to the starter, or should I say back from the starter. I found it easier to install a terminal to one end and hook it to the starter and then work my way back to the battery. For my application it was best to run the cable off the starter and between the header tubes to the frame. Your situation might be different, so make sure to try a few different routes before deciding which provides the most clearance.

12 I ran the cable along the framerail away from the exhaust and secured it with the provided clamps. I used some self-tapping screws, which made this pretty easy.

13 Then I stuffed the end up into the trunk and to the switch. I had an extra foot or so of cable, so I needed to make a cut in the trunk before installing the terminal.

14 Since I didn’t have anymore shrink tube, I just wrapped one with electrical tape. For simplicity’s sake, I pulled the switch back out to install the positive cable ends.

15 After reinstalling the switch, I tightened up the battery terminals and turned the cutoff switch. No sparks, no smoke, so I went and hit the key and the motor fired right up. Now I feel much better about driving the car knowing the battery is secure, the cables are new, and the Optima won’t leak anything.

16 Which Optima Should I Use? There are three different Optima batteries on the market, RedTops, YellowTops, and BlueTops. The RedTop is best suited if your primary need is high power cranking and you are not running aftermarket in-car electronics. The YellowTop is best if you run key-off electronics or if you have a high-demand audio system or multiple electronics and you need the battery to recover from deep power drains. The BlueTop is the marine/RV line and is better suited for those applications.

Read all about the simple process of how to transfer a battery to the truck with Summit Racing's battery relocation and cutoff switch kit. Only at www.chevyhiperformance.com, the official website for Chevy High Performance Magazine! » Read More